1. Field of the Invention
The present invention is directed to an integrated wavelength monitor, more particularly to a wavelength monitor integrated on an optical bench.
2. Description of Related Art
Some radiation sources exhibit wavelength drift over time in excess of that tolerable for many applications. This drift becomes increasingly important as the lifetimes over which these radiation sources are to be deployed increases. Factors such as temperature, age, operating power level, etc., all affect the output wavelength. By monitoring at least one of the direction of the wavelength change, the degree of the change and the percentage of the light being radiated at the different wavelengths, any or all factors which may be causing this change can be modified in accordance with the monitored signal via a feedback loop to stabilize the wavelength of the radiation source. Preferably, both the power and the wavelength are monitored in accordance with known techniques.
Most current wavelength lockers are mounted on a carrier, e.g., a ceramic, to provide support for and connections to the detectors. These solutions include mounting discrete components on a carrier or vertically stacking lithographically formed components, such as set forth, for example, in commonly assigned, co-pending U.S. application Ser. No. 09/543,760 entitled “An Etalon, A Wavelength Monitor/Locker Using the Etalon and Associated Methods” filed Apr. 5, 2000 and U.S. application Ser. No. 09/994,869 entitled “Reduced Noise Wavelength Locker Module” filed Nov. 28, 2001, both of which are hereby incorporated in their entirety for all purposes. While the discrete component solution provides planar packaging, it is not scaleable. While the vertically stacked solution facilitates mass production, it is not a planar package, making it more difficult to handle in automation assembly.
Further, when bonding a glass optical element to a carrier may cause problems due to a mismatch of coefficient of thermal efficiency between these materials. Also, the electrical connections to the detectors on the carrier are realized using wire bonds, which may be too slow and require long leads. Finally, the thermal performance of the carrier is often poor.